Functions of Integers on Cartesian Plane

import scala.math.{min,max}

object Funcij {

  def sumin(n: Int): BigInt = {
    val k: BigInt = n
    k * (k+1) * (2*k+1) / 6
  }
  def sumax(n: Int): BigInt = {
    sumsum(n) - sumin(n)
  }
  def sumsum(n: Int): BigInt = {
    val k: BigInt = n
    k*k*(k+1)
  }
}